In an RLC circuit, power is consumed in the resistance as well as exchanged between the resistance, capacitor, and the supply mains. Let's understand each statement in detail:

**a) Power is consumed in resistance only is equal to I2R:**

In an RLC circuit, the resistance (R) is responsible for dissipating electrical energy in the form of heat. The power consumed by the resistance can be calculated using the formula P = I^2R, where P is the power, I is the current flowing through the resistance, and R is the resistance value. This power is dissipated as heat due to the resistance.

**b) Exchange of power does not take place between resistance and supply mains:**

This statement is incorrect. In an RLC circuit, power is exchanged between the resistance and the supply mains. When an AC voltage is applied to the circuit, the current flowing through the resistance and the voltage across it are in-phase. This means that the power absorbed by the resistance is positive, indicating power flowing from the supply mains to the resistance.

**c) Exchange of power takes place between the capacitor and supply mains:**

This statement is also incorrect. In an RLC circuit, power is exchanged between the capacitor and the supply mains. In an AC circuit, the voltage across the capacitor leads the current flowing through it by 90 degrees. This means that the power absorbed by the capacitor is reactive power, which flows back and forth between the capacitor and the supply mains.

**d) All of the above:**

The correct answer is option 'D' because all of the statements mentioned above are true. Power is consumed in the resistance, exchanged between the resistance and the supply mains, and also exchanged between the capacitor and the supply mains in an RLC circuit.

In summary, an RLC circuit involves the consumption of power in the resistance, as well as the exchange of power between the resistance and the supply mains, and the capacitor and the supply mains. It is important to understand these power exchanges to analyze and design RLC circuits effectively.